Light emitting devices in which light of a discharge lamp or a semiconductor light emitting element is color converted with a fluorescent material have hitherto been used for illumination and the like. In order to generate lights of various colors such as white, in a wide color reproduction range, uniformly with a good color rendering property by mixing blue, red and green color lights, many studies have been made for these light emitting devices. Above all, light emitting devices using a semiconductor light emitting element such as a light emitting diode (LED) or a semiconductor laser (LD) have high luminous efficiency and also have an advantage in terms of environmental protection such as no use of mercury. Accordingly, the development of light emitting devices in which an LED or an LD is combined with a fluorescent material has been actively carried out.
In particular, light emitting devices in which an LED or an LD is combined with an organic red fluorescent material comprising a europium (Eu) complex having an anion of a β-diketone as a ligand have been reported as devices which efficiently absorb light from near-ultraviolet light to visible light and provide high-luminance light emission, compared to a fluorescent lamp using an inorganic red fluorescent material such as Y2O3:Eu (see patent document 1 and patent document 2).
Patent Document 1: JP 10-12925 A
Patent Document 2: JP 2000-509912 A